log_phys_t::apply(): When parsing an INSERT_HEAP_DYNAMIC record,
allow ll==rlen to hold for the last part. A secondary index record
may inherit all preceding bytes from the infimum pseudo-record.

For INSERT_HEAP_REDUNDANT, some header bytes will always be present
because the header will never be copied from the page infimum.
We will tolerate ll==rlen also in that case to be consistent with
the parsing of INSERT_HEAP_DYNAMIC.